The biggest problem I see right now is the first use experience. The first 15 minutes you use a product determines whether you continue using it or likely drop it forever.

When you just start #Nostr & you wanna see anything, all Relays have to be queried first, etc. At first, everything is empty.
Happens as well, when you delete the cache of the #Nostr app you use.

People are so used to instant access, it's probably a pretty big blocker to wait for Relays to finish loading the feed, especially in Global, basically like viewing an image in Internet Explorer during 2003. 

 Could you help mange expectations by a pop up message that says "please hold while we're connecting relays and syncing data.... after that you can connect a wallet, make a post with #???  whatever... and start making friends....". 

 Something to pass the time and educate the user as to what's going on.